2 x ERF in a Nissan Note with room for an adult?!

We've just been in a minor accident and I'm looking at replacing the seats. I'm wondering whether it's sensible to buy an ERF seat now for the baby rather than replace his infant carrier - we've borrowed a Maxi-Cosi infant carrier and could keep using this indefinitely.

Does anyone have 2 ERF seats in a Nissan Note with room for an adult in the middle, at least for shortish trips?

Does the BeSafe IZi Plus take up significantly more room than the Combi? Would the Britax TWE be a better, slimmer option? (If I'm right in thinking it also RFs to 25kg)